Photovoltaic module support system

ABSTRACT

A support system for a solar panel includes a triangular truss with connection points for mounting a photovoltaic module, and a cradle structure that supports the triangular truss and is connected to at least two side supports of the triangular truss. The cradle structure may be driven for rotation about an axis for tracking the sun and several cradle structures can be linked together for tracking movement using a buried linkage system. The truss may also be foldable for ease of transportation and storage.

FIELD OF THE INVENTION

The invention relates generally to photovoltaic systems, and morespecifically to a photovoltaic module support system.

BACKGROUND OF THE INVENTION

Solar energy produced by the sun can be captured by photovoltaic (PV)modules. Mounting systems for PV modules can be fixed or can track thesun's diurnal motion. Typical single axis tracking systems include atorque tube (roughly five feet above grade) capable of rotating a groupof PV modules, which is installed on support posts (driven piles,drilled concrete piles or ballasted foundation). The torque tubesupports one or more PV module support structures and PV modules on thesupport structure (or framed PV modules affixed directly to the torquetube). PV module power plants typically have hundreds or even thousandsof rows of PV modules that are fixed in place and must be rotated totrack the sun's diurnal motion.

FIGS. 1 a-1 c illustrate one example of a typical single axis trackingsystem for PV modules. Multiple PV modules 100 are arranged in parallelrows 400, 500, and 600. The rows 400, 500, 600 generally run in thenorth-south direction, so that PV modules 100 in the rows can be tiltedeast and west to track the sun's rotation. The PV modules 100 aremounted onto a torque tube 115 elevated above the ground by supportposts 104 that may be driven into the ground 110.

At gaps 150 between PV modules 100 in a row 400, 500, 600, a gearbox 101or other rotation point is affixed to the torque tube 115 on either sideof a PV module 100. The gearbox 101 may be driven by independent motorsat each support post 104, or more commonly may be connected by ancantilevered lever arm 102 to a linkage 105 that connects all of theassemblies in a column of the PV array, as illustrated in FIGS. 1 a-1 c.

FIGS. 1 b and 1 c illustrate the rotation of PV modules 100 when thelinkage 105 is driven in a horizontal direction (for example, by amotorized screw mounted to a concrete base at one end of a column), themovement of the linkage 105 and the cantilevered lever arms 102connected to gearboxes 101 causes the PV modules 100 to tilt to trackthe path of the sun. The PV modules may be tilted east or west inaccordance with the movement of the sun. Typically, the rotation point,for example at gearbox 101, is roughly five feet above the ground, andthe linkage 105, when employed, is 2-3 feet above the ground.

There are numerous problems with existing mounting systems such as theone illustrated in FIGS. 1 a-1 c. First, these mounting systems have ahigh center of gravity, due to the rotation point being at the very topof the mounting system. This can be a problem, as solar tracker systemsmust withstand high wind conditions. Second, using independent motors ateach foundation is costly and inefficient. If the rotation points areinstead connected by the linkage 105 illustrated in FIGS. 1 a and 1 b,the linkage 105 impedes on construction, commissioning, and maintenancetraffic flow through the PV array rows. Third, the gearbox 101 used torotate the PV modules 101 and the support posts 104 both require spacebetween the PV modules 100, as illustrated in FIG. 1 a, preventing thePV modules 100 from being placed directly adjacent one another. Thisreduces the effective surface area of the array and is an inefficientuse of real estate. Accordingly, there is a need in the art for atracker system support structure that mitigates these and otherproblems.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 a-1 c illustrate an example support system for a conventionalsingle axis solar tracker array.

FIGS. 2 a-2 c illustrate top down and side views of a support system fora single axis solar tracker array using a truss and cradle assembly inaccordance with an embodiment described herein.

FIGS. 3 a-3 f illustrate top down, side, and perspective views of asupport system for a single axis solar tracker array using a truss andbutterfly cradle assembly in accordance with another embodimentdescribed herein.

FIGS. 4 a-4 c illustrate top down and side views of a support system fora single axis solar tracker array using a truss and cradle assembly inaccordance with another embodiment described herein.

FIGS. 5 a-5 c illustrate top down and side views of a support system fora solar panel array using a truss and cradle assembly in accordance withanother embodiment described herein.

FIGS. 6 a-6 c illustrate top down and side views of a support system fora fixed axis solar panel array using a truss and cradle assembly inaccordance with another embodiment described herein.

FIGS. 7 a-7 k illustrate top down, side, front, and detail views of afolding truss in accordance with an embodiment described herein.

DETAILED DESCRIPTION OF THE INVENTION

In the following detailed description, reference is made to theaccompanying drawings which form a part hereof, and which illustratespecific embodiments of the invention. These embodiments are describedin sufficient detail to enable those of ordinary skill in the art tomake and use them. It is also understood that structural, logical, orprocedural changes may be made to the specific embodiments discussedherein, without departing from the spirit or scope of the invention.

Described herein is support system for photovoltaic (PV) modules in asolar panel array. The support system utilizing a truss and cradleassembly described herein has beneficial structural properties thatenable an increase in the distance between support posts and allows PVmodules to be placed directly adjacent one another in a row, resultingin more efficient usage of real estate. The system also enablesunobstructed passage between array rows during construction,commissioning, and maintenance. Embodiments of the system describedherein enable rotation of multiple rows of PV modules in unison with alow center of gravity rotation point.

FIGS. 2 a-2 c illustrate an embodiment of a PV module support systemutilizing a truss and cradle assembly. Photovoltaic (PV) modules 100 arearranged in parallel rows 700, 800, 900 in a photovoltaic array.Photovoltaic modules 100 in a row 700, 800, 900 are affixed to andsupported by a truss and cradle assembly 202. The truss and cradleassembly 202 supports a manually installed frame and PV module system,or an automated install (cartridge) module support system such asdescribed in U.S. patent application Ser. No. 12/846,621 entitled “AMounting System Supporting Slidable Installation of a Plurality of SolarPanels as a Unit” (filed Jul. 29, 2010), U.S. patent application Ser.No. 12/846,365 entitled “Slider Clip and Photovoltaic Structure MountingSystem” (filed Jul. 29, 2010), U.S. patent application Ser. No.12/846,686 entitled “Apparatus Facilitating Mounting of Solar Panels toa Rail Assembly” (filed Jul. 29, 2010), and U.S. patent application Ser.No. 12/957,808 entitled “Method and Apparatus Providing SimplifiedInstallation of a Plurality of Solar Panels” (filed Dec. 1, 2010), whichare each incorporated by reference herein in their entirety. The trussand cradle assembly 202 is rotatably fixed by a rotary axis 201 to afoundation support 204, which may be driven piles, drilled concretepiles, ballasted foundation, or other suitable support structure.

The truss and cradle assembly 202 at each row 700, 800, 900 of the arrayis driven by an electric motor and gearbox or a hydraulic system that isinstalled on opposite ends of a group of array columns, generally theeast and west ends, as described in more detail below. An undergroundlinkage 220 connected to the drive motors facilitates rotating PVmodules 100 in multiple rows 700, 800, and 900 in unison to track thesun's diurnal motion. Rotation of the truss and cradle assembly 202 ataxis 201 is illustrated in FIGS. 2 b-2 c and is discussed in more detailbelow.

Comparing the system in FIGS. 2 a-2 c to the one in FIGS. 1 a-1 c, it isapparent that the truss and cradle assembly 202 facilitates theformation of rows of PV modules 100 that do not have gaps 150 between PVmodules 100 needed in the FIGS. 1 a-1 c embodiment to provide space forthe gearbox 101. Since the FIGS. 2 a-2 c embodiment does not requirethis gap, longer spans of directly adjacent PV modules, or PV modules ofa longer length than in other systems, can be used, resulting in a moreefficient PV system. Also, the underground linkage 220 enablesunobstructed passage between array rows 700, 800, 900 duringconstruction, commissioning, and maintenance. Further, the system inFIGS. 2 a-2 c has a rotation point that is lower to the ground than thesystem in FIGS. 1 a-1 c. The FIGS. 1 a-1 c system requires a rotationpoint at the very top of the foundation support (about 5 feet above theground), and, when the rows are connected to one another by linkages105, the cantilevered lever aim 102 and linkage 105 hang below thisrotation point. In the FIGS. 2 a-2 c embodiment, however, the samerotation is achieved with a rotation point well below the top of thefoundation structure (the rotation point can be about half as high asthat in the FIGS. 1 a-1 c embodiment, or about 2-3 feet above theground), and with a less obstructive linkage 220. This improvesstability and allows the spacing between foundation supports 204 to beincreased.

FIGS. 3 a-3 f further illustrate aspects of the embodiment of FIGS. 2a-2 c. As illustrated in FIG. 3 a, there are multiple PV modules 100 ineach row 700, 800, 900, 1000, 1100. While one PV module is shown aboveeach foundation support 204 in FIGS. 3 a-3 c, the system can includemany PV modules 100 on the truss 202 between each foundation support, orone PV module 100 may span multiple foundation supports 204. All of therows 700, 800, 900, 1000, 1100 of PV modules 100 are driven by twoelectric motor and gearbox structures 225 installed at each end of thecolumn. Alternatively, a hydraulic system or other motive system canalso be used, as described below.

FIG. 3 c provides a more detailed view of the truss and cradle assembly202. The PV module 100 is attached to a triangular truss 222 byinstallation rails 300 which enable a sliding connection with a recessin the PV modules 100 or a carrier for a plurality of modules in themanner illustrated in U.S. patent application Ser. No. 12/846,621. ThePV modules 100 of this or any other embodiment described herein can alsobe attached to the triangular truss 222 using conventional clips,fasteners, screws, glue or any other suitable mechanism for attaching PVmodules 100 to the triangular truss 222.

The truss 222 is affixed to a cradle 223, which in this embodiment is abutterfly cradle 222 having movable butterfly drive wings 323 andnon-moving (fixed) butterfly drive arms 324. The butterfly drive wings323 are affixed to and support the truss 222, and can be rotated aboutthe axis 201 in either direction. The axis 201 may be a rotation bearingassembly, a gear drive, or any other suitable rotating connection. Theaxis 201 may be biased, for example, by a spring 325 inside a rotationbearing of the axis 201, so that, when not acted upon by another force,the axis will return to a position holding the PV module 100 parallel tothe ground 110 (the orientation illustrated in FIG. 3 c). Other forcesmay be used to bias the axis 201, such as external springs connectedbetween butterfly drive wings 323 and the non-moving butterfly drivearms 324, a programmable microprocessor that returns a gear drive axisto an upright position, or any other mechanism suitable for returningthe PV module 100 to a parallel position when in not being acted upon byanother force. The cradle structure 223 is attached to the foundation204.

Linkages 205 pass through holes in the non-moving (fixed) butterflydrive arms 324, and are connected to the movable butterfly drive wings323. Thus, when a linkage 205 is pulled in a downward direction, it willpull down the respective connected movable butterfly drive wing 323 ofthe cradle 223, which causes the movable butterfly drive wing 323 torotate about axis 201, thus tilting the PV module 100. Linkages 205 maybe a braided metal wire or other moveable connection. A sheath 206around the linkages 205 allows free movement under ground 110, and canbe used to protect the linkages (and as a safety measure) above ground.

In FIG. 3 c, the example support system facilitates rotation of the PVmodule 100 to an orientation of about 45 degrees to either side. Therotation would generally be in the East-West direction, following theorientation of the sun. Greater rotation angles can be achieved by usinga triangle truss 222 and cradle 223 with an acute angle A, providinggreater rotation before reaching the butterfly drive arm 324 of thecradle 223. Similarly, a more restricted rotation can be obtained byusing a triangle truss 222 and cradle 223 with an obtuse angle A.

FIGS. 3 d-3 f provide perspective views of components in the FIGS. 3 a-3c embodiment. FIG. 3 d illustrates two support structures 555 thatinclude foundations 204 and cradle structures 223. The supportstructures 555 have been installed in a row 1000. These supportstructures 555 can support a truss 222, such as the truss illustrated inFIG. 3 e. Multiple support structures 555 in a row may support a singletruss 222.

FIG. 3 e illustrates a perspective view of the truss 222. The truss 222includes top rails 706 connected to side supports 701 and top supports702. Though shown here as a triangular support structure with rail sidesupports 701 and open sides, the truss 222 could also have planar sidesupports 701 that create a continuous side wall on the sides of thetruss 222. The truss 222 may be any length suitable for transport andon-site installation. The truss 222 may be a fixed structure or may be afolding truss (described in more detail below). The top rails 706 may beconfigured with parallel installation rails 300 that enable PV modules100 to be mounted by sliding multiple PV modules 100 onto theinstallation rails 300. Alternatively, a cartridge that holds aplurality of PV modules 100 may be slidably mounted onto theinstallation rails 300 of top rails 706. Though shown here configuredwith installation rails 300 for mounting PV modules 100, any suitablemounting method may be used to affix PV modules 100 to the top rails706, as discussed above. FIG. 3 f illustrates the support structure 555with the truss 222 and PV modules 100 installed.

The tilting of multiple rows of PV modules 100 in unison is nowdescribed with reference to FIGS. 3 a-3 b. In FIGS. 3 a-3 b, theconnection of each row 700, 800, 900, 1000, 1100 by linkages 205 enablesrotation of several rows in unison. In this embodiment, electric motorsand gearboxes 225 at each end of the column provide the necessary forceto move the linkages 205. Multiple electric motors and gearboxes 225 ateach end of the column may be used for long-spanning rows, to providesufficient power to tilt the entire row.

To tilt the PV modules 100, the motor and gearbox 225 at one end of thecolumn retracts the linkage 205, for example by winding the connectedlinkage 205 around a spool 245. When the linkage 205 is retracted, itpulls downward on the movable butterfly drive wing 323 of the connectedcradle 202, and this causes the butterfly drive wing 323 to rotate aboutits axis, tilting the PV modules 100 in one direction. Since all of thecradles 202 in the rows 700, 800, 900, 1000, 1100 are connected bylinkages 205, all of the PV modules 100 in the column are tilted in therespective direction by the tension of the linkages 205 between thecradles 222. To tilt the assemblies 202 back in the opposite direction,the motor and gearbox 225 at the other end of the column retracts theconnected linkage 205, and the PV modules 100 are tilted back in theopposite direction.

The truss and cradle assemblies 202 may be biased into a neutralposition (orienting PV modules parallel to the ground 110) by a spring325 in a rotation bearing of axis 201, or any other suitable biasingstructure. This way, if the electric motors and gearbox 225 fails (dueto power outage or other reasons), the system will maintain this neutralposition. This avoids damage by winds, and inefficiencies that can becaused by a static tilted position.

Retracting linkages 205 using an electric motor and gearbox 225 is oneway to move the rows in unison, but those of skill in the art willrecognize that there are other acceptable ways to tilt these assembliesin unison. For example, if the linkage 220 is sufficiently rigid, motorsand gearboxes 225 are only necessary on one end of the column, as theycould both push and pull the linkages 220 (as opposed to only pulling,as described above). A hydraulic system could also be used at one end ofthe column to both push and pull the linkages 220 to tilt the PV modules100.

FIGS. 4 a-4 c illustrate another embodiment of a PV module supportsystem utilizing a truss and cradle assembly. This embodiment uses asimilar truss and cradle assembly 302, but the cradle is configured withonly one set of drive arms, and instead of being driven by linkages 205connected to an electric motor and gearbox 225 or hydraulics, it isdriven by individual electric actuators 210 located at each foundationsupport. The electric actuators 210 push or pull one side of the trussand cradle assembly 302 to tilt the PV modules 100 in one direction oranother. The electric actuators 210 are connected by an electricalconnection 240 such as a shielded electrically conductive wire. Theelectrical connection 240 is connected, at one end of the PV array, to apower supply 230. As in the other embodiments, the truss and cradleassembly 302 may be biased in a neutral position, so that if there is afailure of the electric actuators 210 or the electrical connection 240,the truss and cradle assembly 202 will return to a neutral position.

FIG. 4 c illustrates a detail view of one of the support structures inthe FIGS. 4 a-4 b embodiment. As illustrated in FIG. 4 c, the PV module100 is connected to the truss and cradle assembly 302 by installationrails 300, but could also be connected using conventional clips,fasteners, screws, glue or any other suitable mechanism for attaching PVmodules 100 to the triangular truss 222. The cradle 423 in thisembodiment has a single set of drive arms 224, unlike thebutterfly-style cradle in FIG. 3 c (which has two sets of arms 323,324). The cradle 423 is rotatably connected to an electric actuator 210which can be a motor-driven or hydraulic actuator. The other end of theactuator 210 is rotatably connected to the foundation 204. When theactuator 210 pushes or pulls on the drive arm 224 of the cradle 423, thePV module 100 is rotated one direction or another. The axis 201 mayallow any desired range of motion, including motion past 45 degrees ineither direction. The actuator 210 can be electrically connected toactuators 210 of other support structures by an electrical connection240, which may be under ground (as illustrated in FIG. 4 c). Theelectrical connections 240 may also be run through the foundation 204 sothat the wires are entirely protected from outside elements.

As with the FIG. 3 a-3 f embodiment, the truss and cradle assembly 302of this embodiment facilitates the use of PV modules 100 which aremounted adjacent one another and without the presence of the PV modulegaps 150 required due to the presence of the gearbox 101 in FIG. 1 a.For this reason, longer PV modules can be used, resulting in a moreefficient array and tracker system. Also, the underground electricalconnection 240 enables unobstructed passage between array rows duringconstruction, commissioning, and maintenance. Further, the system inFIGS. 4 a-4 c has the rotation point that is lower to the ground thanthe system in FIGS. 1 a-1 c, which improves stability and allows thespacing between foundation supports to be increased.

FIGS. 5 a-5 c illustrate yet another embodiment of a PV module supportsystem utilizing a truss and cradle assembly. The FIGS. 5 a-5 cembodiment is essentially the same as the FIGS. 4 a-4 c embodiment (withlike parts identified using like reference numbers), except thisembodiment does not include the attached actuators 210. In thisembodiment, the truss and cradle assembly 302 is not configured with anystructure that would rotate the assembly 302 around the axis 201. Theaxis 201 can be biased using a spring 325 in the axis 201 assembly tomaintain the PV module in the neutral position shown in FIGS. 5 b and 5c.

The FIGS. 5 a-5 c embodiment provides several advantageous features ofthe other embodiments, including a low center of gravity, improvedstructural support, and the ability to use long-spanning PV modules.Additionally, the FIGS. 5 a-5 c embodiment can be upgraded in the futureby adding actuators 210 to provide solar tracking functionality. Thoughillustrated in FIGS. 5 a-5 c with a single drive arm cradle 224 similarto the one in the FIGS. 4 a-4 c embodiment, the FIG. 5 a-5 c embodimentmay also be configured to use the butterfly cradle 223 illustrated inFIGS. 3 a-3 c. If this embodiment is configured with the butterflycradle, a linkage 220 and motor 225 can be added to the structure (asshown in FIGS. 3 a-3 c) as a future upgrade to provide solar trackingfunctionality. In yet another alternative embodiment, the axis 201 ofthe cradle 223 may be removed altogether and the FIGS. 5 a-5 cembodiment may be configured with a fixed (nonmovable) cradle structure224 connected to the foundation 204. Though this embodiment would not beupgradable to a solar tracker system, it would still provide the otheradvantageous structural features described herein.

FIGS. 6 a-6 c illustrate another embodiment of a PV module supportsystem utilizing a truss and cradle assembly. In the FIG. 6 a-6 cembodiment, the truss and cradle assembly is fixed in an angledposition. In one example configuration, the lowest point of the PVmodule may be 18″ above the ground or building structure such as a roof,and the PV module 100 may be angled at a 25 degree angle relative to theground 111 or building structure. As with other embodiments, the use ofa truss and cradle assembly 402 permits the use of long spans ofadjacent PV modules 100, or longer PV modules 100, without requiringgaps 150 in the PV modules for supporting foundations 204. Additionally,the configuration of the truss and cradle assembly 402 with the cradle423 holding the truss 222 at an angle off-center provides a low centerof gravity and improved structural properties as compared to a systemwith a high connection point to the PV module. This, combined with thestructural rigidity offered by the truss 222, allows the foundations 204to be spaced further apart within a row of the PV module array.

The embodiments described herein each include a triangular truss canspans the length of a row in the PV array. The truss 222 may be a fixedtruss that is pre-assembled or assembled on-site, or may be a foldingtruss design. FIGS. 7 a-7 i illustrate top, side, and front views of anembodiment of a folding truss design. In FIGS. 7 a-7 c, the truss 222 isin an unfolded state. The top rails 706 are connected to a bottom boxbeam 703 via side supports 701 attached with pins 710 that provide pivotpoints. Top supports 702 and diagonal supports 704 are attached to thetop rails 706 for additional support. The front view (FIG. 7 c)illustrates the triangular truss shape formed by the folding trussdesign. The triangle truss 222 shown has angles of 90 degrees at angle Aand 45 degrees at angles B, though the triangle truss could be in otherconfigurations, such as an equilateral triangle with 60 degree angles Aand B.

Various mechanisms may be used to hold the truss 222 in the unfoldedstate. For example, the bottom box beam 703 may have indents 750 at thepoint where each side support 701 will come to rest in the unfoldedstate. This is illustrated in FIGS. 7 j and 7 k, which show a top-downview of a segment of the bottom box beam 703 and side support 701. Whenthe structure is unfolded and the side supports 701 are within theindents 750, the bottom box beam 703 will have a tendency not to move ineither direction to fold, especially because the weight on the sidesupports 701 will generally be in a downward direction (towards theground). When sufficient force is placed upon the bottom box beam 703 ina lateral direction, the side supports 701 will move out from theindents 750, as illustrated in FIG. 7 k. Another way to fix thestructure in the unfolded state is to add fixed cross beams to theunfolded structure that would prevent the folding action of thetriangular truss 222. These can be added between adjacent side supports710, between the top supports 702 and the bottom box rail 703, or to anytwo points that would prevent the folding action described below anddepicted in FIGS. 7 d-7 i. Any suitable method of fixing the truss inthe open state can be used to prevent folding of the truss 222.

FIGS. 7 d-7 f illustrate the truss 222 as it is in the process of beingfolded. The bottom box beam 703 comes forward and up, and will fold inthe indicated direction until it meets the top rails 702. The pins 710on side supports 701 provide a rotation point, and hinges 720 allownecessary articulation for the bottom box beam 703 to move up andforward, towards the top rails 702.

FIGS. 7 g-7 i illustrate the truss 222 in a folded position. Here, thebottom box beam 703 rests against the top rails 702 of the triangulartruss structure. The hinges 720 of the side supports 701 have folded toallow articulation of the bottom box beam 703, and the side supports 701have fully pivoted about rotation points provided by pins 710. Thefolding truss 222 enables easy transportation and storage of the trussuntil it is commissioned for use in an installation. The folding truss222 can be used in fixed PV module arrays or in solar tracker systems.

While embodiments have been described in detail, it should be readilyunderstood that the invention is not limited to the disclosedembodiments. Rather the embodiments can be modified to incorporate anynumber of variations, alterations, substitutions, or equivalentarrangements not heretofore described without departing from the spiritand scope of the invention.

What is claimed as new and desired to be protected by Letters Patent ofthe United States is:
 1. A support system for a solar panel comprising:a triangular truss with connection areas for mounting at least onephotovoltaic module thereon; and a cradle structure adapted to besupported on a foundation and supporting the triangular truss, saidcradle structure connected to at least two side supports of thetriangular truss, wherein the cradle structure comprises a rotatingaxis, the support system further comprising: a pair of butterfly drivewings extending from the axis and oriented with an angle of less than180 degrees between them, the butterfly drive wings configured to rotateabout the axis of the cradle structure; and an actuator connected to thepair of butterfly drive wings, wherein the butterfly drive wings areconnected to the triangular truss, and wherein the actuator provides aforce that rotates the butterfly drive wings about the axis.
 2. Thesystem of claim 1, wherein the cradle structure is connected to andsupported by the foundation, and wherein the actuator is connected tothe foundation.
 3. A support system for a solar panel comprising: atriangular truss with connection areas for mounting at least onephotovoltaic module thereon; and a cradle structure adapted to besupported on a foundation and supporting the triangular truss, saidcradle structure connected to at least two side supports of thetriangular truss, wherein the triangular truss is a folding truss that,when in a folded position, occupies less space in at least one directionthan when unfolded, and wherein, when the folding truss is in the foldedposition, a bottom beam of the folding truss, rests against a pluralityof top rails of the folding truss.